Thyroid function test (TFT)

A thyroid function test (TFT) is a biochemical blood test that measures the levels of thyroid hormones in the blood to assess how well the thyroid gland is working: 

Here are the common thyroid function tests along with their normal reference ranges:

1. TSH (Thyroid-Stimulating Hormone):

   • Normal Range: 0.4 - 4.0 mIU/L
   • Interpretation:
     • High TSH: Hypothyroidism
     • Low TSH: Hyperthyroidism

2. Free T4 (Free Thyroxine):

   • Normal Range: 0.8 - 1.8 ng/dL
   • Interpretation:
     • High Free T4: Hyperthyroidism
     • Low Free T4: Hypothyroidism

3. Free T3 (Free Triiodothyronine):

   • Normal Range: 2.3 - 4.2 pg/mL
   • Interpretation:
     • High Free T3: Hyperthyroidism
     • Low Free T3: May indicate hypothyroidism

4. Total T4 (Total Thyroxine):

   • Normal Range: 5.0 - 12.0 μg/dL
   • Interpretation: Provides overall thyroid hormone levels

5. Total T3 (Total Triiodothyronine):

   • Normal Range: 80 - 200 ng/dL
   • Interpretation: Provides overall thyroid hormone levels

6. Thyroid Antibody Tests:

   • TPOAb (Thyroid Peroxidase Antibodies):
     • Normal Range: <35 IU/mL
     • High levels suggest autoimmune thyroid disease (e.g., Hashimoto's thyroiditis, Graves' disease)
   • TgAb (Thyroglobulin Antibodies):
     • Normal Range: <20 IU/mL
     • High levels suggest autoimmune thyroid disease
   • TSI (Thyroid-Stimulating Immunoglobulin):
     • Normal Range: <1.3 IU/L
     • High levels indicate Graves' disease